The city is historically significant because it was the center of activities for the 'Katipunan', the secret militant society that launched the Philippine Revolution during the Spanish occupation of the Philippines. In a house in Caloocan secret meetings were held by Andrés Bonifacio and his men, and it was in the city's perimeters where the first armed encounter took place between the 'Katipunan' and the Spaniards.
In 1899 the city saw heavy fighting in the Philippine–American War, at the Battle of Caloocan and the Second Battle of Caloocan.
During the formation of the province of Rizal, Caloocan was included in its matrix until 1975.
Caloocan once encompassed a much bigger area without being bisected into north and south. The district of Balintawak, La Loma and Novaliches were once part of Caloocan. Balintawak is a historic district because it was the original site of the "Cry of Pugad Lawin" (Unang Sigaw sa Balintawak) at a location called "Kang-kong" near Tandang Sora's house. Novaliches was an expansive sector with some hillsides that served as meeting places and hideouts for Andres Bonifacio and the Katipunan.
By the 1920s, the consolidation of several municipalities, Caloocan had annexed the neighbouring town of Novaliches, as stated in the Act 942, as amended by Acts 984 and 1008 of the Philippine Commission, bringing its total area to about 15,000 hectares extended to the foothills of Marikina, San Mateo and Montalban in the east; Tinajeros, Tanza and Tala rivers in the North; San Francisco del Monte, Sampalok, Sta. Cruz and Tondo in the south; and Dagat-Dagatan or Aromahan in the west.
When Quezon City was created in 1939, 1,500 hectares of land from Caloocan, the following barrios or sitios: Balintawak, Balingasa, Kaingin, Kangkong, La Loma, Malamig, Matalahib, Masambong, Galas, San Isidro, San Jose, Santol and Tatalon, was to be given to the new capital city. Instead of opposing it, Caloocan residents willingly gave land to Quezon City in the belief it will benefit the Country's new capital.
However, in 1949, Congress passed Republic Act No. 333, which redefined the Caloocan-Quezon City boundary. The barrios of Baesa, Talipapâ, San Bartolomé, Pasong Tamó, Novaliches, Banlat, Kabuyao, Pugad Lawin, Bagbag, Pasong Putik, which once belonged to Novaliches and had an area of about 8,100 hectares, were excised from Caloocan. The remaining portion of the Novaliches is now what we call North Caloocan. This caused the division of Caloocan into two parts, the southern section being the urbanised portion, while the northern section becoming suburban-rural.
Caloocan is divided into two non-contiguous areas. Southern Caloocan lies directly north of the Manila and is bounded by Malabon and Valenzuela to the north and west, Navotas to the west, and Quezon City to the east. Northern Caloocan is the northernmost territory of Metro Manila which most residents call Novaliches, Caloocan; it lies east of Valenzuela, north of Quezon City, and south of San Jose del Monte, Meycauayan and Marilao in the province of Bulacan. Caloocan's northern part is much larger than its southern half.
Caloocan is divided into 188 barangays. The city uses a hybrid system for its barangays. All barangays have their corresponding numbers but only a few — mostly in the northern part — have corresponding names. However, names of barrios and districts do not necessarily coincide with barangay perimeters. Barangays in southern Caloocan are smaller compared to their northern counterparts.
Among the cities in Metro Manila, only Manila, Pasay and Caloocan implement the so-called "Zone Systems". A zone is a group of barangays in a district. Although a zone is considered a subdivision in the local government units, the people do not elect a leader for the zone in a popular election similar to the normal barangay or local elections. The zoning system is merely for statistical purposes. Caloocan has 16 zones. The biggest zone in Caloocan is Zone 15 in District 1 (North Caloocan) directly west of the second biggest zone in Caloocan which is Zone 16.
Barangay Bagong Silang (176) is the most populous barangay in the entire country with a population of 246,515 people.
In 1957, the sitio of Bagbagin was separated from the barrio of Kaybiga and converted into a distinct barrio known as barrio Bagbagin.
As of 2015, the city has a population of 1,583,978 people, which makes it the fourth largest city in the Philippines in population. Under the same census year, Caloocan South (Barangays 1 to 164) has a population of 585,091 and Caloocan North (Barangays 165 to 188) has a population of 998,887.
The population density of Caloocan (28,387 persons per square kilometer) surpasses that of the NCR population density.
Of the country’s 238 legislative districts (LDs), the First LD of Caloocan was the biggest in terms of population size, with 1.19 million persons.
Most residents speak both Filipino and English, with considerable numbers speaking other languages and dialects.
Like many other places in the country, Roman Catholicism is the predominant religion. There is a significant presence of Iglesia ni Cristo and other Protestant churches.
Caloocan's 10th Avenue area is well known for the clusters of motorcycle dealers and motorcycle spare parts dealers. Among the major and famous streets are P. Zamora Street and A. Mabini Street.
Numerous banks have branches in the city such as Banco de Oro, East West Bank, MetroBank, Maybank, Chinabank, Bank of the Philippine Islands, Our Lady of Grace Credit Cooperative, etc.
The city also has a number of shopping malls and stand-alone supermarkets and hypermarkets including Puregold Maypajo,Monumento and Caloocan, Victory Central Mall, Puregold Monumento, Araneta Square, Uniwide Warehouse Club Monumento, SM Hypermarket Monumento, and SM Center Sangandaan which are in Monumento area in the south. Savemore Market Kiko Camarin and iMall Camarin in Barangay 178 (Kiko Camarin) , Zabarte Town Center, Savemore Market Zabarte, and Puregold Zabarte, are shopping malls in Barangay 175 Camarin area at the north. Puregold Deparo, which is opened last November 2015, and Ultra Mega Supermarket Deparo are stand-alone supermarkets at Barangay 168 Deparo which serves the residents of Deparo and the nearby barangays of Bagumbong and Llano.
Manila North Tollways Corporation (the concession holder of the North Luzon Expressway), is headquartered in Caloocan.
The LRT-1 has a terminal at Monumento that passes through the city's 5th Avenue LRT Station. The railway traverses Rizal Avenue Extension and enters the City of Manila and Pasay City. The stretch can be traveled in about 30 minutes. Philippine National Railways also has a line, with its terminal at Samson Road, and passes through Caloocan railway station, Asistio Avenue railway station, and C-3 railway station.
The city has an extensive network of roads, the most prominent being Epifanio de los Santos Avenue, which begins in the Monumento area. The North Luzon Expressway's Operations and Maintenance Center and the motorway's Balintawak Toll Barrier are in Caloocan.
Bus line Victory Liner Incorporated has its headquarters and terminal along in Rizal Avenue Extension near the Monumento Station.
The city's most celebrated landmark is the monument to the revolutionary Andrés Bonifacio, which stands on a roundabout at the northern terminus of EDSA. The memorial was erected in 1933, and consists of an obelisk with sculptures by National Artist Guillermo Tolentino. The monument marks the very first battle of the Philippine Revolution on 3 August 1896.
Recent renovations have been made on the environs of the monument, including the Bonifacio Circle, its former site, and the Caloocan stretch of EDSA, which is 100 metres away from the landmark. The whole area is known as 'Monumento'.
City hall stands along A. Mabini Avenue in the southern part of the city, across the street from San Roque Parish Cathedral. The old city hall stands today at 9th Avenue. There is a city hall in the northern part of the city. The city's District Office of the Bureau of Internal Revenue is along EDSA.
The Caloocan City Police Station is under the parent agency National Capital Region Police Office's Northern Police Districtof the Philippine National Police.
The city's one public university is the University of Caloocan City (formerly Caloocan City Community College in 1971 and Caloocan City Polytechnic College in 1975). Other educational institution of higher learning are the University of the East Caloocan, ABE International Business College, Holy Redeemer School of Kalookan, World Citi Colleges, Caloocan Central Elementary School and Manila Central University.
Several high schools, such as Caloocan National Science and Technology High School (North Caloocan's first-ever science and technology high school; its students are admitted if they pass a competitive examination), Caloocan City Science High School, Caloocan City Business High School, Caloocan High School, Maria Clara High School, Notre Dame of Greater Manila, Bagumbong High School (Main and Annex), Camarin High School, Tala High School, Manuel Luis Quezon High School, Sampaguita High School, Cielito Zamora High School, Bagong Silang High School, National Housing Corporation High School (NHC HS), Kalayaan National High School, Deparo High School, Guardian Angel School, Holy Infant Montessori Center, Saint Benedict School of Novaliches, Saint Dominic Savio School of Caloocan City, Saint Andrew School MHANLE Inc., Philippine Cultural College (Annex), Northern Rizal Yorklin School, Systems Plus Computer College, St. Mary's Academy of Caloocan City, St. Gabriel Academy, Asian Institute of Computer Studies - Caloocan, St. Clare College of Caloocan, Mystical Rose School of Caloocan, Holy Angel School of Caloocan Inc., Immaculada Concepcion College, St. Agnes Academy of Caloocan Inc., St. Therese of Rose School, Young Achievers School of Caloocan, St. Joseph College of Novaliches, Our Lady of Lourdes Catholic School, Maranatha Christian Academy of Caloocan (Camarin), Kasarinlan High School, Camarin Elementary School and the two campuses of La Consolacion College (one is in Novaliches in the northern part and the other is on the southern part, near city hall).
There is a campus of Access Computer College, AMA Computer College Campus, a degree-awarding tertiary educational institution and STI Academic Center Caloocan at the Samson Road Road corner Caimito Road in front of UE Caloocan.Calamba, LagunaMalabon, Metro ManilaSan Jose del Monte, Bulacan Incheon, South Korea